IU Simon Cancer Center dermatologist gives tips to protect yourself against skin cancer


INDIANAPOLIS -- (July 20, 2010) -- This summer’s heat and humidity are good reminders to protect your skin from the sun’s harmful rays.

Lawrence A. Mark, M.D., Ph.D., an assistant professor of dermatology at the Indiana University School of Medicine and a researcher at the Indiana University Melvin and Bren Simon Cancer Center, said, “You can’t see the sun’s harmful rays, you can’t feel them, but they can harm you.”

Dr. Mark recommends these tips for protection against the sun: 

  • Apply sunscreen with an SPF of at least 30. Dr. Mark explained SPF this way: If your skin begins to redden after being in the sun for one minute, you could expect to be in the sun for 30 minutes while wearing an SPF of 30 before you see the same amount of reddening.
  • Wear appropriate clothing, such as a wide brim hat, long-sleeved shirt, and long pants.
  • The sun’s rays are strongest from 10 a.m. to 3 p.m. or so. Limit long periods of time outdoors during these hours.

According to the American Cancer Society (ACS), most of the more than one million cases of skin cancer diagnosed yearly in the United States are considered to be sun-related. Basal cell carcinoma and squamous cell carcinoma are the most common forms of skin cancer. Melanoma is the deadliest form of skin cancer, and it can appear suddenly on any part of the body or develop from a mole. 

What should you look for?

Dr. Mark tells patients to watch for what he calls the “ugly duckling” sign. “If you have a spot that just doesn’t look like any other, it is best to have a doctor examine it, just to be on the safe side,” he said. He advises people to know their bodies and talk with their physicians about any changes they notice. Also be mindful that skin cancer can develop in places you may not consider: between the toes, on the soles of the feet, on the palms of the hands, under finger and toe nails, and on oral or genital mucous membranes.  

Dr. Mark and his colleagues use the ABCD’s to evaluate melanoma: 

  • A, asymmetry: half of a mole or birthmark does not match the other half
  • B, border: edges are irregular, ragged, notched, or blurred
  • C, color: the color isn't the same all over but may have differing shades of brown or black, sometimes with patches of red, white or blue
  • D, diameter: the area is larger than six millimeters (about the size of a pencil eraser) or is growing larger

If detected and treated early, these cancers have a greater than 95 percent cure rate.